In accordance with variety of the modes of use of the information processors, information processors capable of being used in response to each situation are required. There are a notebook (or clamshell) computer and a tablet computer as one type of a portable computer which is information processor. To respond to both the modes of use, there is a portable computer which can also be used as the notebook computer by connecting an extension device comprising a keyboard, etc. to the tablet computer. The portable computer functions as a notebook computer by allowing the tablet computer to be inserted into a connection terminal of the extension device coupled by a hinge.
In general, in the notebook computer, the operation control of turning off a display unit when the display unit is overlaid on a keyboard—so called “closed state”—, and activating the display unit when the display unit is made to stand up from the closed state—so called “open state”—, is often executed. To the contrary, in the tablet computer, the display unit is activated when the computer is used since the “closed state” and the “open state” cannot be distinguished from each other.
Therefore, for the portable computer having the functions of both the notebook computer and the tablet computer, the operation control of the display unit should be changed in accordance with the modes of use of the portable computer when used as the notebook computer or used as the tablet computer. In addition, not only for the display unit but also for input units such as a keyboard of an extension device, etc., it should be judged which the mode of use of the portable computer is, and should be choose a suitable operation control in accordance with the determined mode of use.